Tapped fastener



W -/d /4 [Ii mg. 31, 1948. A. P. BRUSH 2,448,351

' TAPPED FASTENER Filed Jan. 23, 1946 INVENTOR Patented Aug. 31, 194.8

UNITED STATES PATENT OFFICE 2,448,351 TAPPED FASTENER Abbott P. Brush, Greenwich, Conn.

Application January 23, 1946, Serial No. 642,851

2 Claims.

The invention here disclosed relates to tapped fasteners and is a continuation in part of the invention covered in patent application, Serial No. 541,074, filed June 19, 1944, issued as United States Patent No. 2,393,606, January 29, 1946.

In some installations it is desirable that the inserted portion of the fastener, that is, the part forming the tapped hole for the screw, be seated flush or below the surface of the material in which the insert is mounted.

Also, for mounting in some of the softer materials it is desirable that the insert be made to cut into the material.

Special objects of the present invention are to provide a fastener which will meet these particular requirements and which at the same time will incorporate the self-locking features of the basic invention covered in the patent identified.

Other special objects of the invention are to provide a fastener having the characteristics and advantages mentioned, which will be small in overall dimensions so that it may be used in places where space is limited and which will be generally practical and eflicient for fastener pur poses.

Other desirable objects and the novel features by which the purposes of the invention are attained are set forth or will appear in the course of the followin specification.

' The drawing accompanying and forming part of the specification illustrates certain present embodiments of the invention but structural details may be modified and changed as regards the immediate illustration, all within the true intent and proper scope of the invention as hereinafter defined and claimed.

Figure l in the drawing is a side elevation and broken sectional view showing one of the fasteners in position for driving in a hole of the size for which it is designed.

Figure 2 is a similar view showing the fastener insert driven flush in the hole and locked against rotation, and Figure 2a is a section on line 2a2a of Fig. 2.

Figure 3 is a similar view showing the screw entered and the fastener insert locked against withdrawal as well as against rotation.

Figures 4, 5 and 6 are views corresponding to Figures 1, 2 and 3 illustrating a form of the fastener designed for mounting in a thin panel.

The body of the insert, as in the patent identified, is in the nature of a tubular stud l beveled or tapered at 8 at the entering end and slotted from that end inwardly to near the opposite end.

. 2 at 9 to divide the shank portion of the device into separated segments.

The unslotted, driving end of the stud is shown as having a cylindrical screwthreaded passage Ill therethrough, continued and extending at lfla down the inner faces of the split apart segments.

The conical end portions 8 of the segments, in the first form of the invention illustrated, terminate in a relatively abrupt shoulder l I providing on the segments, external, sharp, substantially semi-circular cutting edges l2. These partly circular shoulders in the form of the. unit as illustrated in Figure 1 are of greater diameter than the drilled or punched hole [3 in which the unit is to be used.

Above the sharply defined shoulder H the shank of the insert may be substantially cylindrical or tapered slightly from the top downward to said shoulder substantially as indicated at M.

The second form of the invention illustrated differs from that first described in that the shoulder back of the front or end bevel 8 is somewhat less abrupt, being indicated in Figure 4 as a flat abevel or cone l 5.

Where the device is to be used in materials such as wood and some of the softer plastics and is to be fully embedded, the first form of the invention may be employed.

i Either before or in the act of driving, the seg-,

ments are collapsed or converged as indicated in Figure 2 and in driving the element in this condition, the sharp cutting edges H3 at the opposite sides of the slot adjoining the shoulder ll, being of greater diameter than the hole, cut into the material at the sides of the hole forming keyways I! which lock the insert as so driven against rotation in the hole.

The taiper M of the headless shank may be such as to make a tight drive fit as the element is hammered into the flush position indicated in Figure 2. Locked rotatively and held longitudinally by the slight taper drive fit in the hole the insert is fully secured and may be left indefinitely in the condition shown in Figure 2, ready to receive a screw whenever it is to be put to use.

Figure 3 shows how with entry of the screw the segments will be forced apart and the sharp circular edges l2 be caused to bite into the surrounding material. This wedging apart also causes the segments to act as levers drawing the insert down more firmly into seated relation in the hole. This final drawing down, as shown in Figure 3, may establish a slight clearance at 18 between the driven end of the stud and the surf-ace of the material. This is of advantage in enabling the screw l9 to draw a supported object 20 up tight and flat against the face of the panel or support 2| in which the hole is formed. 5

For mounting in a thinner panel, the form of the invention shown in Figures 4, 5 and 6 may be preferred.

The action of this second form is substantially as described except-what; in passings-through the? :10

layer of thinner material','the lessabrupt shoulder l5 will engage the back edge of the hole and then operate as a toggle to pull the stud more firmlyiv down in its seat as the screw is inserted, Figurecfi.

In both forms of the invention the screw is '1 irictionally held and retained in the insert which,-

driving, thesmaller tapered ends of the-shank segments may actually come together, as indicated in Figure 2. Inthis relation thesegments will have been collapsed sufiici'ently to bring-the outer edges'of the circul-arshoulders, across the slotldown toapproximately the diameterof the hole so ,asnot to materially cutaway the material of .the hole inhthis driving operation.

W'h'at is claimed is: 1. A hammer driven headless self-securing screw seat forming insert adapted to be anchored 1 and .secured .againstrotation in a circular hole by a simple driving operation and comprising'a fiat ended headlesstubularstud: having a split tubular..shank for. anchoring; and holding .it

against rotation, said sha'nk havinga beveled. 40

conical tapered end portion for entry in the hole anda' sharply angledsho'ulde'r meeting-interme= diate the'length of-the' shank in a sharply ole-- fined annular ridge normallypircular incross section, "said tubular shank: extending from the- 5 opposite .end inwardly on ,a slight "taperto said abruptly angled shoulder'and beingslott-ed inwardly in a single 'wide slot extending'longitudinally from the tapered -entry-end"past =said shoulder and thereby separated into t/wo'opposed segments, said stud having a circular screwthreaded passage through the headless flat 'driving end of the same and continuations of said same screw passage on the opposing inner faces of the separated shank segments and said two separated shank segments being convergently collapsed toward each other in sharply angled relation and in contacting engagement so that the opposing Walls of the slotted portion at said normally circular annular ridge will form inclined cuttin'; "edges to dig into'ethe oppbsiteisides of the'wall of a circular hole-into which the-insert is driven.

2. A hammer driven self-securing screw seat forming. insert adapted to be anchored and securedagainst rotation in a circular hole by a simpleihammer' driving operation and comprising a blunt ended generally cylindrical tubular stud having' a tapered conical end portion for entry in .the..hole, said conical end portion enlarging to a maximum diameter, said maximum diameter portion being normally circular in cross section and located intermediate the overall lengtnof the stud and 'connectedwitnthe generally cylin drical portion of the stud by an abruptly? 'angledxi' shoulder, said stud being slotted inwardly from; said entry end in a single Wideislot :extendirig beyond said abruptly angled shoulder into said generally cylindrical portion an'd'therebydividing the'stud into two widely separated opposed-segments, said slot having substantially parallel side walls forming outstandingsharpedgeswhere said walls intersect the normally circular maximum diameter portion and'said'tubular' stud having a substantially cylindrical passage the-rethr'ough;

said segments being sharplyinclined'toward each ABBOTT PJBRUSHL REFERENCES CITED The following references are "of record'in the file of this" patent:

UNITED STATES PATENTS Number Name Date" 1,978,935 Douglas Oct. 30', 1934 2,370,327 Rosan Feb; 27,1945 2,379,786 Bu'gg=' July'3, 1945 

